Apt Holman Preamplifier Review (vintage Audio)

[Ericco]

“Better”?

Certainly different.

For me, “better” is simply more transparent, less affected (unchanged or altered) or as little as possible.

What Peter Williams did to a 35 year old preamp was, simply, magic.

so I bought an APT, liked what I heard (and didn’t), sent it to Quirk for a tuneup and, wow.
I have it running into a TEKTRON Tk2 2a3/50I-S with EML 300b PT’s right now and am working through my Miles Davis vinyl collection- at the Dig-Cookin‘- Workin’ era (mid-late 50’s bebop) right now enjoying the investment enormously.

You might too.

Great Miles! Yes, I might pick up an APT and Quirkify it, or maybe Quirkify my NAD... I'll have to confer with him. Thanks!

 

[EJ3]

Question - I have been using an NAD 1300 Pre with a Bryston 3B for many years. Wondering if the Abt Holman, a vintage Bryston or other pre under $1k might be a worthwhile upgrade in search of better sound?

Just found this at Quirk Audio and it seems to partially answer my question. https://quirkaudio.com/?p=1144

I own a pair of APT/Holman's Pre-Amps & Peter is the last person to have his hands on the internals. & I am extremely happy with them.
May I suggest that at this stage of your NAD 1300's life, that it should get the Peter's touch.
In the meantime, perhaps you should obtain (perhaps from Peter @ quirkaudio) an Apt/Holman preamp to put in place before you send your NAD 1300 to Peter @ quirkaudio.
Then you put the Apt in the 1300's place (so that you won't have a lapse in ability to play your music) & send out your 1300 to be gone through.
Upon the 1300's return, then you can compare the 2.
Perhaps you will like one better than the other for whatever reason and you decide to keep that one in the system.
Then you could either start putting together a second system (for your house or perhaps for a loved one).
Or you could sell the one that you decided was less to your liking. It may be that they are both equally good audibly but you like a certain feature set better or the one that you are used to using.
Doing this would give you many options.
My many experiences in dealing with Peter @ quirkaudio (with my ADVENT 300, my pair of APT/Holman Pre Amps, my 6 NAD 2200's, my 2 NAD 2100's have all had his hands on them) have been among the best (if not the best) service experiences that I have ever had.
EJ3

 

[NormB]

Great Miles! Yes, I might pick up an APT and Quirkify it, or maybe Quirkify my NAD... I'll have to confer with him. Thanks!

Played a bunch of other stuff like Lumineers, Michael Hedges, El Ten Eleven, Kodaline - the more recent stuff for my kids, 26 and 30 who were suitably wowed by the overall sound, too.

This is a keeper. Plus I have another ADCOM 565 preamp I use for a garage stereo (LOUD… has small venue JBL speakers, JRX 125s driven by monoblocked GFA-555 II’s) should I want to switch it up again, but having the TWO turntable inputs makes a difference as I have a TT I play mono LP’s on.

Keep us posted.

 

[Ericco]

I own a pair of APT/Holman's Pre-Amps & Peter is the last person to have his hands on the internals. & I am extremely happy with them.
May I suggest that at this stage of your NAD 1300's life, that it should get the Peter's touch.
In the meantime, perhaps you should obtain (perhaps from Peter @ quirkaudio) an Apt/Holman preamp to put in place before you send your NAD 1300 to Peter @ quirkaudio.
Then you put the Apt in the 1300's place (so that you won't have a lapse in ability to play your music) & send out your 1300 to be gone through.
Upon the 1300's return, then you can compare the 2.
Perhaps you will like one better than the other for whatever reason and you decide to keep that one in the system.
Then you could either start putting together a second system (for your house or perhaps for a loved one).
Or you could sell the one that you decided was less to your liking. It may be that they are both equally good audibly but you like a certain feature set better or the one that you are used to using.
Doing this would give you many options.
My many experiences in dealing with Peter @ quirkaudio (with my ADVENT 300, my pair of APT/Holman Pre Amps, my 6 NAD 2200's, my 2 NAD 2100's have all had his hands on them) have been among the best (if not the best) service experiences that I have ever had.
EJ3

Yes, I've been through that repair route. When the 1300 died a couple of years ago, I had it repaired locally (at least one board had to be rebuilt). While it was out, I took my NAD 3020 out of storage and used it as a pre into the Bryston. I actually thought it was a bit better sounding than the 1300. When the 1300 came back it sounded a little better than before the repair and everything works now.

The 3020 has issues with the phono and aux inputs which I may address at some point. When I had my larger house, I had the 3020 in the office and the 1300/Bryston in the family room.

BTW, I've been using the Bryston since '84 when I bought it used. It was in the shop in the '90's but has worked flawlessly since then. I'm also a pro bassist and used to run it bridged to power my bass rig. Truly built to last!

 

[Ericco]

Yes, I've been through that repair route. When the 1300 died a couple of years ago, I had it repaired locally (at least one board had to be rebuilt). While it was out, I took my NAD 3020 out of storage and used it as a pre into the Bryston. I actually thought it was a bit better sounding than the 1300. When the 1300 came back it sounded a little better than before the repair and everything works now.

The 3020 has issues with the phono and aux inputs which I may address at some point. When I had my larger house, I had the 3020 in the office and the 1300/Bryston in the family room.

BTW, I've been using the Bryston since '84 when I bought it used. It was in the shop in the '90's but has worked flawlessly since then. I'm also a pro bassist and used to run it bridged to power my bass rig. Truly built to last!

Update - While considering sending the NAD 1300 to Peter, a Bryston SP1.7 (with the BP 25 analog stage) came up for a great price so I got it.
Am really enjoying it and will use the NAD as my phono pre.

 

[EJ3]

Thank you, thats pretty clear.

Here the full factory original specs, including all inputs (including the buffers in the 2 tape loops) & all outputs:
Rated Specifications top

Intro Specifications Measurements Usage Recommendations



Tom Holman has many pages of specifications and how to measure them in the Apt Holman Preamplifier Service Manual. I'd recommend you read this cover-to-cover if you're interested, as it not only explains many of the novel circuit innovations, it even includes several sample projects to build in order to measure the excruciatingly high performance and low noise of this preamplifier!



Inputs

Phono

2 Phono inputs.

The first has selectable resistance and capacitance, while the second is fixed at 47kΩ and 50 pF.

100 mV maximum at 1 kHz, inverse RIAA, warp-proof.

The right channel of each of the two phono inputs is internally adjustable ±2 dB for perfect channel balance.



Line

All line inputs are 50 kΩ in parallel with 330 pF.

Unselected inputs are terminated with 2.2 kΩ.

Maximum input level: 10 V RMS (+20 dBV or +22 dBm).

3 line-level inputs.

2 tape monitor loops.

1 external processor loop, for a total of six line-level and two phono inputs!



Gain, Polarity and Volume Control

18 dB maximum gain from line inputs.

Phono preamp gain: 36.5 dB at 1 kHz: 5 mV for 2 V output, 1.25 mV for 0.5 V output.

All outputs are non-inverting.

Volume control rated to track left-right to within 1 dB over the entire range. I'm impressed: this is a very important parameter, and this is the only preamp I've ever seen which bothers to specify it.

The multiwiper 10 kΩ volume control has 32 clicks, or 31 intervals, at 10º per click, or room for 36 clicks in 360.º

The volume control uses individually trimmed thick-film resistors to ensure precise channel-to-channel tracking.



Outputs

Two MAIN outputs, fed in parallel. Provisions on the circuit board to allow your technician to insert a fixed resistive pad in the path of the MAIN 2 output if this optimizes the gain structure for your power amplifier.

330 Ω source impedance, 5 kΩ/3,000 pF maximum load.

Two tape outputs: 100 Ω source impedance, 10 kΩ/1,000 pF maximum load.

One external processor output.

One ¼" headphone output from a separate amplifier.



Output Levels

2 V RMS for rated specifications.

7 V RMS maximum undistorted.

If loaded with 2 kΩ, 3 V RMS maximum.

10 V RMS from the separate headphone amplifier.



Frequency Response

20 - 20,000 Hz ±0.5 dB, with ultrasonic and ultrasonic filters active.

RIAA EQ ±0.5 dB 30 - 15,000 Hz.



Selectable 15 Hz Infrasonic filter (rear panel switch)

Within 0.5 dB at 20 Hz, -3 dB at 15 Hz and > -30 dB at 5 Hz.

Group delay 4 mS at 50 Hz.

If the filter isn't selected, the -3 dB point is 8 Hz.



Ultrasonic Filter (automatically engaged when Tone Controls active)

Within 0.5 dB at 20 kHz, -3 dB at 40 kHz, and -18 dB at 100 kHz.

Group delay 7 µS.

Interchannel delay: < 0.5 µS. (the limit of audibility is 10 µS.)

When the tone controls are defeated, the -3 dB point is 150 kHz.



High Filter (only active with Tone Controls selected)

-3 dB at 8 kHz.



Distortion

Less than 0.01% THD at rated output (2V) and lower.

Less than 0.01 % SMPTE intermodulation distortion (60/7k Hz 4:1) at rated output (2V) and lower.

Less than 0.005% DFD with 19 kHz and 20 kHz mixed 1:1, at rated output (2V) and lower.

Less than 0.006% (-84 dB) TIM with 3.18 kHz square and 15 kHz sine mixed 4:1 peak-to-peak, low-pass filtered at 6 dB/octave at 100 kHz, at rated output (2V) and lower.



Noise (all A-weighted RMS)

Phono, measured with standard IHF cartridge

-74 dB down from 5 mV RMS at 1 kHz. Typically -76 dB.

Noise figure: 4 dB, 2 dB typical.

-90 dBV output noise with volume control at -20 dB.



Line

-106 dBV equivalent input noise.

-95 dBV output noise with volume control at minimum.

-95 dBV output noise with volume control at -20 dB.



Hum

Typically equal to or less than the the wideband noise spectrum.



Crosstalk

< -65 dB at 1 kHz.

< -45 dB at 20 kHz.

< -90 dB from unselected inputs.

When tested, feedthrough from unselected inputs was inaudible.

 

[DSJR]

Working in the West End of London back then and having a curious manager always willing to try new products, I know we had the Rappaport thing (ugh) and much talk of the Apt Holman, but simply can't remember if we actually got one to try sadly. The UK's 'terrible two' were beginning their stranglehold amongst the UK audio scene which was largely populated by hippies in their thirties listening to CSN&Y, Little Feat and some jazz-rock stuff and all the 'classical music' buffs were a generation above who simply couldn't understand the new wave of the times (it nearly killed Quad off at least once in the 80's I remember) and we went hugely down a blind alley in the 80's there and many survivors are keeping it alive too although the products have changed a lot and do perform better now - at horrendous prices.

Both my inherited Crown IC150's are ageing badly now and both have non-critical faults to their basic transparency (controls getting crabby, one has no delay on switch-on and the hf filter on the other only works on one channel) - see the Ken Rockwell test. I have a couple of more modern alternatives I can use but a vintage unit like this is so 'right' for my old stereo owners of such a unit would be encouraged to get it properly serviced and enjoy it as the great preamp it is.

 

[EJ3]

I have a pair, both done by Peter @ Quirk Audio and, sometime in the first quarter of 24 I am going to (in conjunction with the SCHIIT SYN) do this:
Quadraphonic Synthesis

With two Holman Preamplifiers, you can synthesis and control four output channels from just two input channels.

Apply all your inputs to the first Holman Preamplifier. Use it for all your tone controls, filters and source and tape selections. Leave its Stereo Mode in Stereo.

Connect the first Holman Preamplifier's MAIN 1 output to one power amplifier and your two front speakers.

Connect the first Holman Preamplifier's MAIN 2 output to any line-level input of the second Holman Preamplifier.

Connect the second Holman Preamplifier's MAIN 1 output to the power amplifier for your two rear speakers.

Rotate the second Holman Preamplifier's stereo mode control to L-R, and start by setting it to about unity gain or a bit less, and keep its tone controls flat. The tone and filter settings of the first Holman Preamplifier are fed automatically to the second Holman Preamplifier.

Set balance on the first preamp. Set front-rear balance on the Volume control of the second preamp.

Leave the power switch of the second preamp ON, and plug its power cord into a switched outlet of the first Holman Preamplifier. Now the power is controlled by the first Holman Preamplifier, too.

This plan has now changed (as my wife has been gone (overseas) since Nov 3, 22 & will be back Feb 28, 24).
So it will be likely 1st quarter of 24 before I can do this & see how it works out.
My plan also now calls for obtaining a Schiit Syn to put into this so that I can manipulate the analog signal & have a sub out (I wish that the Syn had at least 2 sub outs, in a stereo configuration).

 

[EJ3]

owners of such a unit would be encouraged to get it properly serviced and enjoy it as the great preamp it is.

YES!; owners of such a unit would be encouraged to get it properly serviced and enjoy it as the great preamp it is.

 

[EJ3]

Does it take unleaded? Have seatbelts? Here I am with Amir.

None of the people I know that have older performance cars DO NOT HAVE SEATBELTS. In fact, 90+ percent of them of them have TRUE full seatbelt setups with H harness setups or 5 click anti-submarine seatbelts (as in having to pass MUCH HIGHER stringent tests than the crappy seatbelts that come in most cars these days) in order to get a SEMA certification.
As to the lo/no lead non-issue, I can buy up to 114 octane unleaded if I want but most Pontiac engines that I have worked on (from 1968 & newer) had ZERO need for unleaded fuel.
As all of the combustion chambers for Pontiac engines were flame hardened at the factory since that date, anyway.
I know of no one building engines for street, tip, road racing or any other common use for ICE engines that wants to go back to leaded fuels.
This is actually HILARIOUS coming from someone with a handle that says "don't trust authority.

 

[NormB]

I’m now the proud owner of a SECOND unit courtesy of ePay’s bidding site, and for a few bucks less than the previous one.

This one looks BRAND NEW inside, with very little, if any, dust/oxidation that I can see, nothing’s been touched/removed and it works GREAT so far. I took it down to my house in TN for the last two weeks playing into an ADCOM 545-II amp and Klipsch RM-600 speakers, streaming from an iPod mostly with a lightning-RCA stereo cable adapter.

Hope to send it in to Peter for upgrades next month after other bills are paid.

40 year old capacitors and op-amps gotta go.

 

[mhardy6647]

and op-amps gotta go.

Do op amps wear out?

 

[NormB]

Do op amps wear out?

Ha-ha.

No. Specs improve.

Compare TL072 with OPA2134. I replaced 30 year-old ADCOM OEM (and REVOX sound repro board) opamps with these and noticed immediate improvements.

What I"m after is as sonically neutral a "processor" as possible with a preamp. The APT-Holman - for my money and listening level - and Quirk Audio's upgradesmeet my needs ("need"... such a funny word).

YMMV.

 

[Doodski]

Quirk Audio

It's nice the website is back up and operational.

 

[EJ3]

Working in the West End of London back then and having a curious manager always willing to try new products, I know we had the Rappaport thing (ugh) and much talk of the Apt Holman, but simply can't remember if we actually got one to try sadly. The UK's 'terrible two' were beginning their stranglehold amongst the UK audio scene which was largely populated by hippies in their thirties listening to CSN&Y, Little Feat and some jazz-rock stuff and all the 'classical music' buffs were a generation above who simply couldn't understand the new wave of the times (it nearly killed Quad off at least once in the 80's I remember) and we went hugely down a blind alley in the 80's there and many survivors are keeping it alive too although the products have changed a lot and do perform better now - at horrendous prices.

Both my inherited Crown IC150's are ageing badly now and both have non-critical faults to their basic transparency (controls getting crabby, one has no delay on switch-on and the hf filter on the other only works on one channel) - see the Ken Rockwell test. I have a couple of more modern alternatives I can use but a vintage unit like this is so 'right' for my old stereo owners of such a unit would be encouraged to get it properly serviced and enjoy it as the great preamp it is.

I liked Little Feat well enough.
The Crowns: I ran into them a lot in small to moderate P.A. systems.
I hope that you would be able to find someone to fix those up for not too much money.
I've never seen measurements of them (other than what the factory put out then) but I had a friend that ran some with a pair of his Dahlquist DQ-10's that were some of the few amplifiers that I heard at the time that seemed to power those well (this was all new gear, back in the day).

 

[EJ3]

I’m now the proud owner of a SECOND unit courtesy of ePay’s bidding site, and for a few bucks less than the previous one.

This one looks BRAND NEW inside, with very little, if any, dust/oxidation that I can see, nothing’s been touched/removed and it works GREAT so far. I took it down to my house in TN for the last two weeks playing into an ADCOM 545-II amp and Klipsch RM-600 speakers, streaming from an iPod mostly with a lightning-RCA stereo cable adapter.

Hope to send it in to Peter for upgrades next month after other bills are paid.

40 year old capacitors and op-amps gotta go.

That make 2 of us that have two of the APT/Holman Preamps. Both of mine have been in Peter's place for his resto-modding.
A highly recommended process to have done, IMHO!

 

[DSJR]

I liked Little Feat well enough.
The Crowns: I ran into them a lot in small to moderate P.A. systems.
I hope that you would be able to find someone to fix those up for not too much money.
I've never seen measurements of them (other than what the factory put out then) but I had a friend that ran some with a pair of his Dahlquist DQ-10's that were some of the few amplifiers that I heard at the time that seemed to power those well (this was all new gear, back in the day).

The Crown D-60 and 150 power amps just run and run, although one D-60 suffered a driver transistor internal fatigue (not unheard of when apparently the internals of said transistors can 'disconnect' with age) - Do I really need two sets of inherited bridged D-60's plus a conventional 'stereo' one? It's the preamps which still work, but which visually and operationally I'd love to update (you rarely see the Crown SL2/PSL2 here and used and these are damned close to a Schiit Kara in price... I have analogue sources too, so a decent preamp is mandatory here whatever I do speakerwise in the future. I've read tales of the well built UK era Audiolab 8000Q line preamp having capacitor bulging issues (was this the time - late 90's - of bad Chinese made copy-caps?). For now, the IC-150's do work for now...